Tracking a Changing Climate
Orange-crowned Warbler: arriving earlier
In recent years, Orange-crowned Warblers have tended to arrive earlier than average, changing at a rate of 2.6 days per decade.
Swainson's Thrush: no change
So far, there has been no detectable change in Swainson's Thrush arrival dates over time.
Wilson's Warbler: arriving later
In recent years, Wilson's Warblers have tended to arrive later than average, changing at a rate of 1.1 days per decade.
Fox Sparrow: no change
So far, there has been no detectable change in Fox Sparrow arrival dates over time.
Golden-crowned Sparrow: arriving earlier
In recent years, Golden-crowned Sparrows have tended to arrive earlier than average, changing at a rate of 2.1 days per decade.
Hermit Thrush: no change
So far, there has been no detectable change in Hermit Thrush arrival dates over time.
Ruby-crowned Kinglet: arriving earlier
In recent years, Ruby-crowned Kinglets have tended to arrive earlier than average, changing at a rate of 1.8 days per decade.
Point Blue staff and interns collect weather data several times each day at the Palomarin Field Station to understand how climate change (over the long-term) and weather fluctuations (over the short-term) affect birds. Weather plays a huge role in the daily lives of birds, from successfully raising young to surviving the winter, while climate change can affect the long-term stability of bird populations.
Recent warming at Palomarin
To examine long-term weather patterns, we calculated annual average temperatures and total rainfall at Palomarin since 1976. Both measures have fluctuated over the last 40+ years, but temperatures have recently become much warmer. Through 2018, the most recent year of data included here, the hottest year we’ve recorded was in 2017. The wettest year we’ve recorded was in 1997-98 (during a strong El Niño). Recent years have been relatively dry, punctuated by a few wet winters.
Why is tracking weather and climate important for bird conservation?
Understanding how birds are affected by weather and climate requires long-term monitoring over decades. Because of our long-term bird monitoring and weather data collection at Palomarin, Point Blue has been able to identify changes in both the bird populations and the local climate, and uncover the links between them. This information helps us understand how well birds are adapting to climate change, and which species may be more vulnerable to climate change and may require more conservation attention. Here are just a couple examples of how our research has identified how birds are responding to global climate change.
Migration Timing
A changing climate may influence the seasonal timing (“phenology”) of blooming plants, hatching insects, and bird migration or nesting. In some cases, birds may not be able to easily change the timing of their migration to keep up with changes in the timing of their plant and insect food supplies, while others are shifting to try to stay in sync.
We have examined the dates migratory species arrive at Palomarin in the spring, and found that some species are arriving earlier (Orange-crowned Warbler), some are arriving later (Wilson’s Warbler), while others haven’t changed at all (Swainson’s Thrush).
For species that arrive at Palomarin in the fall, some species are arriving earlier (Golden-crowned Sparrow and Ruby-crowned Kinglet), while others haven’t changed at all (Fox Sparrow and Hermit Thrush).
The timing of bird arrivals in spring is thought to be adapted to the timing of food availability for successfully raising young, which may also be shifting with climate change. The timing of bird arrivals in fall may reflect warmer temperatures and a longer nesting season to our north. It’s not yet clear whether birds that are shifting the timing of their migration are able to keep up with changes in their environment, or why some birds aren’t yet changing the timing of migration at all. Future research could examine whether individuals that arrive earlier or later are more successful in raising young or surviving the winter, whether the optimal arrival time has changed over the years, and whether it depends on how far the birds are migrating.
Body Size
Birds at Palomarin have been getting longer wings! A 2012 study led by graduate student Rae Goodman uncovered this surprising finding using banding data from Palomarin and the San Francisco Bay Bird Observatory. Studies from other parts of the world have found that birds are getting smaller, thought to be related to increasing temperatures. Longer wings could indicate birds in California are getting larger, possibly in response to increasing variability in our climate or more favorable conditions than in other places.
To understand why birds have been getting longer wings, future research could examing whether birds with longer wings arrive at to the Palomarin Field Station at different times than birds with shorter wings, or whether they are better at raising young or surviving the winter.
How did we collect these data?
The tools have changed over time, but we have been collecting weather data on site since 1968, including daily records of precipitation, fog, temperature, cloud cover, wind, and barometric pressure. The bird body size and arrival dates data come from our long-term mist netting and banding operation. All of these data are collected by staff, volunteers, and especially the hundreds of interns who have trained at Palomarin over the years.
Plan your visit!
Although the Palomarin Field Station is currently closed to the public, we welcome you to plan your visit in the near future. You can see our weather station and watch how we collect weather data during a bird banding demonstration. Visitors can drop in and join our intern and staff biologists to learn how we collect this data — and hopefully see a bird in the hand! More information on visiting and scheduling groups.